JPH09300173A - Method and system of cooling main spindle of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the temperature difference between a main spindle and a main bed by supplying cooling oil in proportion to each main spindle rotation, so that some main spindles whose rotation are slow or in waiting condition may not be suppled with much amount and not be over cooled. SOLUTION: When the control system 60 detects from S cord in the NC program that a main grinding spindle 34 is running and a base surface machining main spindle 35 and a finish machining are in waiting condition, the control system 60 orders to switch a solenoid valve 49 to flow to a path 52a and the large amount of cooling oil passes through a throttle valve 55 and is supplied to a main grinding spindle 34, and a solenoid valve 48 switches to a path 51b and a solenoid valve 47 switches to 59b. By virtue of such arrangements, the base surface machining main spindle 35 and the finish machining main spindle 36 will be supplied through small throttle valve 57, 56 respectively, thereby small amount of cooling oil is supplied to these shafts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to spindle cooling of a machine tool having a plurality of spindles.

[0002]

2. Description of the Related Art Generally, a spindle of a machine tool generates heat due to rotation of a spindle driving motor and a bearing, and a temperature difference is generated between the spindle and a bed supporting the spindle. This temperature difference causes a difference in thermal displacement between the spindle and the bed, and the position of the tool tip attached to the spindle shifts, reducing machining accuracy.Therefore, cooling oil is supplied to the spindle to drive the spindle drive motor, which is a heat source, and Cooling oil is circulated around the outer circumference of the bearing to absorb heat generated from the main shaft.

A machine tool for cooling such a spindle is shown in FIG. 4, and a spindle cooling mechanism and a spindle cooling method will be described below with reference to FIG. This machine tool has 3
It has three main spindles 9, 10 and 11, and a tool (not shown) is attached to each of them to process a workpiece (not shown). Then, only one of the main spindles 9, 10 and 11 processes the workpiece, and the remaining non-machined main spindles rotate at a low speed so as to reach a predetermined rotation speed immediately during the machining. Waiting in the state of.

The cooling oil cooled by the cooling device 1 in such a state is supplied to the main shafts 9, 10, 11 through the outward path 8 and the heat generated by the main shafts 9, 10, 11 is absorbed to raise the temperature of the cooling oil. The temperature is detected by the temperature detector 3 immediately before returning to the cooling oil tank 2 through the return path 7. The cooling device 1 operates according to a command from the control device 4 so that the difference between the temperature detected by the temperature detector 3 and the temperature of the bed 6, which is the reference temperature detected by the reference temperature detector 5, becomes constant, The temperature of the cooling oil is adjusted.

When the machine tool is in operation, the spindle in the low speed standby state also generates heat due to its rotation, so that the cooling oil is supplied to both the spindle in the processing state and the low speed standby state.

[0006]

However, since the cooling oil supplied to the main spindle is cooled to the temperature for cooling the main spindle in the working state, the temperature is lower than that of the main spindle in the stand-by state, resulting in overcooling. Tends to be in a state. Due to this supercooling, a thermal displacement difference occurs between the main spindle and the bed in the standby state. This thermal displacement difference is good when the required machining accuracy is not so severe, but there is a problem in that the machining accuracy is deteriorated during high-precision machining.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first aspect of the present invention is a method for cooling a spindle of a machine tool for cooling a plurality of spindles. It is characterized in that a cooling oil having a flow rate proportional to the number of rotations of the main shaft is supplied to each main shaft for cooling.

According to a second aspect of the present invention, in a spindle cooling device of a machine tool including a plurality of spindles and a cooling device for cooling the plurality of spindles, the flow rate of cooling oil supplied to each of the spindles is different. Adjusting means for adjusting, detecting means for detecting the number of revolutions of each of the main spindles, and control means for controlling the adjusting means so that the flow rate is proportional to the number of revolutions of each of the main spindles detected by the detecting means. It is characterized by having. (Operation) Cooling oil is cooled by the cooling device, and the adjusting means is controlled by the control means to supply the cooling oil at a flow rate proportional to the number of revolutions of each spindle to each spindle to cool it, so that it is in standby at a low speed. State spindle does not become supercooled.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG. In FIG. 3, reference numeral 32 denotes a bed, and an X-axis guide base 31 fixed on the bed 32 is provided with a table 29 that is reciprocally moved in the vertical direction (X-axis) in the figure by a servomotor 28. This table 2
A headstock 30 is fixed to the headstock 9. The headstock 30 rotatably supports a grinding spindle 34, a reference surface machining spindle 35, and a finishing machining spindle 36.

A Z-axis guide stand 33 is fixed on the bed 32 on the left side of the X-axis guide stand 31 in the figure, and the Z-axis guide stand 33 is moved by the servo motor 21 in the left-right direction (Z
A column 22 that reciprocates on the shaft is provided. The column 22 is driven by the servo motor 23 in the direction perpendicular to the paper surface (Y
A work headstock 37 that reciprocates on the shaft is provided, and the work headstock 37 is provided with a work spindle 24. A chuck 25 that detachably holds a workpiece 26 is fixed to the workpiece spindle 24. When the workpiece 26 is machined, the grinding spindle 34 rotates at high speed, the reference surface machining spindle 35 rotates at low speed, and the finishing machining spindle 36 rotates at medium speed. Three
Only one of the spindles 4, 35, and 36 is machined, and the remaining spindles are standing by while rotating at low speed.

Reference numeral 27 is a cooling device, and 40 is each spindle 3.
This is a cooling oil tank for storing the cooling oil circulated through 4, 35 and 36. In FIG. 1, reference numeral 46 denotes an outward path of a pipe for supplying the cooling oil cooled by the cooling device 27 to the main shafts 34, 35, 36, and 45 denotes the main shaft 34,
The cooling oil supplied to the cooling oil tanks 40 and 35 is supplied to the cooling oil tank 40.
It is the return route of the pipe for returning to. Reference numeral 61 is an adjusting means for adjusting the flow rate of the cooling oil supplied to the respective main shafts 34, 35, 36 through the forward path 45.

As shown in FIG. 2, in the adjusting means 61, the outward path 46 is branched into three pipes 50, 51 and 52 on the way. A solenoid valve 47 is arranged in the pipe 50, and the pipe 5
Reference numeral 0 is branched to the pipes 50a and 50b on the downstream side of the solenoid valve 47. The pipe 50a is provided with a large flow rate throttle valve 53, and the pipe 50b is provided with a small flow rate throttle valve 56. A solenoid valve 48 is arranged in the pipe 51, the pipe 51 is branched into pipes 51a and 51b on the downstream side of the solenoid valve 48, a large flow throttle valve 54 is arranged in the pipe 51a, and a small flow valve is arranged in the pipe 51b. A flow rate throttle valve 57 is arranged. The solenoid valve 49 is arranged in the pipe 52, and the pipe 52 is connected to the solenoid valve 4
9 is branched into pipes 52a and 52b on the downstream side, and a large flow throttle valve 55 is arranged in the pipe 52a.
A small flow rate throttle valve 58 is arranged in the. The openings of the large flow rate throttle valves 53, 54, 55 are set to the respective main shafts 34, 3
It is set so that the cooling oil can be supplied at a flow rate according to the heat generated by the rotation of the components 5 and 36 in the working state. Further, the opening degree of the small flow rate throttle valves 56, 57, 58 is set so that the cooling oil can be supplied at a flow rate according to the heat generated by the rotation of the main shafts 34, 35, 36 in a standby state at a low speed. Has been done.

In FIG. 1, a cooling oil 43 is supplied to each of the main shafts 34, 35 and 36, and circulates around the main shaft drive motor and bearings (not shown) which are heat sources to absorb heat and raise the temperature. A temperature detector for detecting the temperature of the cooling oil immediately before returning to the cooling tank 40 through the return path 45,
Reference numeral 44 is a reference temperature detector for detecting the temperature of the bed 32 which is the reference temperature. Then, the cooling device is instructed by the control device 42 so that the difference between the temperature of the bed 32, which is the reference temperature detected by the reference temperature detector 44, and the temperature detected by the temperature detection air heater 43 becomes constant. 27 operates to adjust the temperature of the cooling oil.

Reference numeral 59 denotes a memory, which stores an NC program for controlling each control axis (X axis, Y axis, Z axis) for machining the workpiece 26. The rotation speed of each spindle is described by the S code that specifies the rotation speed. One of a plurality of spindles is selected according to the NC program, and the workpiece 26 is machined at the rotation speed described in the program.

A control device 60 detects the number of revolutions of each main shaft designated by the S code in the NC program stored in the memory 59, switches the solenoid valves 47, 48, 49 and controls each control shaft. Is. Next, the spindle cooling method in the above configuration will be described. When the workpiece 26 is processed, the reference surface processing spindle 35, the grinding spindle 34, and the finishing spindle 36 are machined in this order.

First, the controller 60 detects from the S code in the NC program that the reference surface machining spindle 35 is in the machining state and the grinding machining spindle 34 and the finishing machining spindle 36 are in the standby state. Then, the electromagnetic valve 48 is switched to the flow path 51a side by a command from the control device 60, a large flow of cooling oil is supplied to the reference surface processing main shaft 35 through the large flow rate throttle valve 54, and the electromagnetic valve 49 is operated. 52b side, solenoid valve 4
7 is switched to the side of the flow path 50b, and the grinding main spindle 34 and the finishing main spindle 36 have small flow rate throttle valves 58, 5 respectively.
A small flow rate of cooling oil is supplied through 6.

Next, the controller 60 detects from the S code in the NC program that the grinding spindle 34 is in the machining state, and the reference surface machining spindle 35 and the finishing machining spindle 36 are in the standby state. Then, the electromagnetic valve 49 is switched to the flow path 52a side by the command of the control device 60, a large flow of cooling oil is supplied to the grinding spindle 34 through the large flow throttle valve 55, and the electromagnetic valve 48 is connected to the flow path. The 51b side and the solenoid valve 47 are switched to the flow path 50b side, and a small amount of cooling oil is supplied to the reference surface processing main spindle 35 and the finishing processing main spindle 36 through the small flow rate throttle valves 57 and 56, respectively.

Next, the controller 60 detects from the S code in the NC program that the finishing machining spindle 36 is in the machining state, and the grinding machining spindle 34 and the reference surface machining spindle 35 are in the standby state. Then, the solenoid valve 47 is switched to the flow passage 50a side by a command from the control device 60, a large flow of cooling oil is supplied to the finishing spindle 36 through the large flow throttle valve 53, and the solenoid valve 49 is connected to the flow passage. The 52b side and the solenoid valve 48 are switched to the flow path 51b side, and a small flow rate of cooling oil is supplied to the grinding spindle 34 and the reference surface machining spindle 35 through the small flow throttle valves 58 and 57, respectively.

Next, when the controller 60 detects from the S code in the NC program that the grinding spindle 34, the reference surface machining spindle 35, and the finishing machining spindle 36 are all in the standby state, control is performed. Solenoid valve 4 according to command from device 60
7, the solenoid valve 48 is switched to the flow channel 51b side, the solenoid valve 49 is switched to the flow channel 52b side, and the grinding spindle 34,
A small amount of cooling oil is supplied to the reference surface processing main shaft 35 and the finishing processing main shaft 36 through the small flow rate throttle valves 56, 57 and 58, respectively.

As described above, when machining the workpiece 26,
Switching the solenoid valve according to the S code in the NC program,
A large flow rate of cooling oil is supplied to the spindle in the machining state, and a small flow rate of cooling oil is supplied to the spindle in the standby state at a low speed. Moreover, the machining accuracy does not decrease due to the difference in thermal displacement between the bed and the spindle. Further, when the temperature of the cooling oil supplied to the plurality of spindles is adjusted to cool each of the spindles, as many cooling devices as the number of spindles are required, but since the cooling is performed by adjusting the flow rate, one A plurality of spindles can be cooled by a cooling device.

In the embodiment of the present invention, the rotation speed of the spindle is detected from the S code in the NC program. However, the rotation speed of the spindle may be detected by using some device such as an encoder. May be.

[0022]

As described above, according to the present invention, cooling oil having a flow rate proportional to the rotational speeds of a plurality of main spindles is supplied to each main spindle to cool it. Since it does not become a supercooled state and there is no difference in thermal displacement between the spindle and the bed, high precision machining is possible. Further, when the temperature of the cooling oil supplied to the plurality of spindles is adjusted to cool each spindle, cooling devices are required for the number of spindles, but the present invention adjusts the flow rate of the cooling oil supplied to each spindle. Since the cooling is performed by using the single cooling device, it is possible to cool the plurality of spindles according to the usage status of each spindle.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an adjusting unit according to the embodiment of the present invention.

FIG. 3 is a plan view of the machine tool according to the embodiment of the present invention.

FIG. 4 is a schematic view of a conventional spindle cooling method.

[Explanation of symbols]

 27 Cooling device 32 Bed 34 Spindle for grinding 35 Spindle for reference surface machining 36 Spindle for finishing 40 Cooling oil tank 42 Controller 43 Temperature detector 44 Reference temperature detector 47-49 Solenoid valve 53-55 Throttle valve for large flow rate 56-58 Throttle valve for small flow rate 59 Memory 60 Control device 61 Adjusting means

Claims (2)

[Claims] 1. A spindle cooling method for a machine tool for cooling a plurality of spindles, wherein a cooling oil having a flow rate proportional to the number of revolutions of each spindle is supplied to each spindle for cooling. Spindle cooling method for machine tools. 2. A spindle cooling device for a machine tool, comprising a plurality of spindles and a cooling device for cooling each of said spindles,
Adjustment means for adjusting the flow rate of the cooling oil supplied to each of the main shafts, detection means for detecting the number of revolutions of each of the main spindles, and flow rate proportional to the number of revolutions of each of the main spindles detected by the detection means And a control means for controlling the adjusting means as described above.